I know on chevy 350s theres a small yet significant little mod that simply connects the inlet and outlet hose on the throttle body for the coolant to pass through, called the throttle body bypass. They claim it makes about 10 give or take a few HP (or should i say recovers lost HP from the water pump). I was looking at the schematics in the bentley and we have a similar throttle body coolant passage and i was wondering if it was possible to do something like this on our m42s. I am NOT looking to make easy HP, simply trying to take off as much load on the engine as possible.
Actually, it's not that it recovers lost HP because the coolant pump has less work, it's that it doesn't add heat to the air charge as it enters the engine. Cold air is better for power, right, so why heat it as it enters?
That being said, I did it on my 1996 Impala SS and didn't notice any significant difference.
The idea behind having the warmer plate is to prevent the throttle body from icing - if you live in a warm enough area, it is not necessary.
Really, though, the amount it warms the air charge is negligible (consider just how long the air is actually in the throttle body on it's way through your engine), and for the work involved, I would say it is not worth the effort. If yours is leaking, then by all means, cap it off, but other than that...